Display device and method of manufacturing the same

ABSTRACT

A display device includes: a substrate; a first thin film transistor and a second thin film transistor arranged over the substrate; a display element connected to the first thin film transistor; a wiring connected to the second thin film transistor and including a first wiring layer and a second wiring layer; a pattern insulating layer arranged between the first wiring layer and the second wiring layer; a planarization layer covering the wiring; and a connection electrode arranged on the planarization layer and connected to the first wiring layer and the second wiring layer respectively through a first contact hole and a second contact hole.

This application claims priority to Korean Patent Application No.10-2019-0071070, filed on Jun. 14, 2019, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND 1. Field

One or more embodiments relate to a display device and a method ofmanufacturing the display device.

2. Description of Related Art

A display device is an apparatus that visually displays an image ofdata. The display device typically includes a substrate divided into adisplay area and a non-display area. In such a display device, a gateline and a data line may be arranged in the display area and insulatedfrom each other. The gate line and the data line may intersect with eachother to define a plurality of pixels in the display area. Also, a thinfilm transistor and a pixel electrode may be provided to each pixel areain the display area, and the pixel electrode may be electricallyconnected to the thin film transistor. Also, an opposite electrode maybe provided in the display area, and the opposite electrode may beprovided in the pixel areas in common. Various wirings, a gate driver, adata driver, a controller, etc. for transferring an electric signal tothe display area may be provided in the non-display area.

SUMMARY

One or more embodiments include a display device that displays an imagewith improved quality. However, it should be understood that embodimentsdescribed herein should be considered in a descriptive sense only andnot for limitation of the disclosure.

According to an embodiment, a display device includes a substrate, afirst thin film transistor disposed over the substrate, a second thinfilm transistor disposed over the substrate, a display element connectedto the first thin film transistor, a wiring connected to the second thinfilm transistor, where the wiring includes a first wiring layer and asecond wiring layer, a pattern insulating layer disposed between thefirst wiring layer and the second wiring layer, a planarization layercovering the wiring, and a connection electrode disposed on theplanarization layer and connected to the first wiring layer and thesecond wiring layer through a first contact hole and a second contacthole, respectively.

In an embodiment, a bottom surface of the second wiring layer may have asame area as an area of a top surface of the pattern insulating layer.

In an embodiment, a lateral surface of the second wiring layer may beconnected to a lateral surface of the pattern insulating layer.

In an embodiment, the display element may include a pixel electrode, anemission layer, and an opposite electrode, and the connection electrodemay include a same material as a material of the pixel electrode and bedisposed in a same layer as the pixel electrode.

In an embodiment, an area of the first wiring layer may be differentfrom an area of the second wiring layer.

In an embodiment, the planarization layer may contact a lateral surfaceof the pattern insulating layer.

In an embodiment, the display device may further include a capacitorincluding a first electrode and a second electrode, where the firstelectrode may include a same material as a material of a gate electrodeof the first thin film transistor, and the second electrode may overlapthe first electrode, include a same material as a material of the firstwiring layer, and may be disposed in a same layer as the first wiringlayer.

In an embodiment, the display device may further include a biaselectrode disposed below the first thin film transistor.

In an embodiment, the bias electrode may be connected to a sourceelectrode or a drain electrode of the first thin film transistor.

In an embodiment, the wiring may include a data line providing a datasignal to the second thin film transistor.

In an embodiment, the display device may further include a thin-filmencapsulation layer covering the display element, where the thin-filmencapsulation layer may include a first inorganic encapsulation layer,an organic encapsulation layer, and a second inorganic encapsulationlayer, which are stacked one on another.

In an embodiment, the display device may further include a sealingsubstrate disposed opposite to the substrate.

According to an embodiment, a method of manufacturing a display deviceincludes providing a thin film transistor and a first wiring layerconnected to the thin film transistor over a substrate, sequentiallyproviding an insulating layer and a conductive layer on an entire topsurface of the substrate to cover the first wiring layer, providing aphotoresist pattern on the conductive layer, forming a second wiringlayer and a pattern insulating layer by etching the conductive layer andthe insulating layer using the photoresist pattern as an etch mask, andproviding a connection electrode connecting the first wiring layer andthe second wiring layer.

In an embodiment, a bottom surface of the second wiring layer may have asame area as an area of a top surface of the pattern insulating layer.

In an embodiment, a lateral surface of the second wiring layer may beconnected to a lateral surface of the pattern insulating layer.

In an embodiment, a display element of the display device may include apixel electrode, an emission layer and an opposite electrode, and theconnection electrode may include a same material as a material of thepixel electrode and be disposed in a same layer as the pixel electrode.

In an embodiment, an area of the first wiring layer may be differentfrom an area of the second wiring layer.

In an embodiment, the method may further include providing aplanarization layer covering the first wiring layer, the second wiringlayer and the pattern insulating layer before the providing theconnection electrode.

In an embodiment, the method may further include providing a capacitor,where the capacitor may include a first electrode and a secondelectrode, the first electrode may include a same material as a materialof a gate electrode of the thin film transistor, and the secondelectrode may overlap the first electrode, may include a same materialas a material of the first wiring layer, and may be disposed in a samelayer as the first wiring layer.

In an embodiment, the method may further include a bias electrodedisposed below the thin film transistor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of embodiments of the disclosure will bemore apparent from the following description taken in conjunction withthe accompanying drawings, in which:

FIG. 1 is a plan view of a display device according to an embodiment;

FIGS. 2A to 2C are equivalent circuit diagrams of one of the pixels of adisplay device according to embodiments;

FIG. 3 is a cross-sectional view of a display device according to anembodiment;

FIGS. 4 to 11 are sequential cross-sectional views of a method ofmanufacturing a display device according to an embodiment;

FIG. 12 is a cross-sectional view of a display device according to analternative embodiment; and

FIG. 13 is a cross-sectional view of a display device according toanother alternative embodiment.

DETAILED DESCRIPTION

The invention now will be described more fully hereinafter withreference to the accompanying drawings, in which various embodiments areshown. This invention may, however, be embodied in many different forms,and should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. Like reference numerals refer tolike elements throughout.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

It will be understood that when a layer, region, or component isreferred to as being “on” another layer, region, or component, it can bedirectly or indirectly on the other layer, region, or component. Thatis, for example, intervening layers, regions, or components may bepresent.

Sizes of elements in the drawings may be exaggerated for convenience ofexplanation. In other words, since sizes and thicknesses of componentsin the drawings are arbitrarily illustrated for convenience ofexplanation, the following embodiments are not limited thereto.

When a certain embodiment may be implemented differently, a specificprocess order may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order.

It will be understood that when a layer, region, or component isreferred to as being “connected” to another layer, region, or component,it may be “directly connected” to the other layer, region, or componentor may be “indirectly connected” to the other layer, region, orcomponent with other layer, region, or component interposedtherebetween. For example, it will be understood that when a layer,region, or component is referred to as being “connected to orelectrically connected” to another layer, region, or component, it maybe “directly electrically connected” to the other layer, region, orcomponent or may be “indirectly connected or electrically connected” toother layer, region, or component with other layer, region, or componentinterposed therebetween.

Herein, a display device is an apparatus that displays an image and mayinclude a liquid crystal display, an electrophoretic display, an organiclight-emitting display, an inorganic light-emitting display, a fieldemission display, a surface-conduction electron-emitter display, aplasma display, and a cathode ray display.

For convenience of description, embodiments where a display device is anorganic light-emitting display device will hereinafter be described indetail, but embodiments of a display device according to the disclosureis not limited thereto and may be variously modified to be one of othertypes of display device.

Hereinafter, embodiments of the invention will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a plan view of a display device according to an embodiment.

Referring to FIG. 1, an embodiment of the display device includes adisplay area DA and a peripheral area PA, which is a non-display areasurrounding the display area. Pixels PX including a display element arearranged in the display area DA and provide a predetermined image.

In an embodiment, each pixel PX emits, for example, red, green, blue orwhite light, and may include, for example, an organic light-emittingdiode. In such an embodiment, each pixel PX may further include a devicesuch as a thin film transistor TFT and a capacitor.

Herein, a pixel PX represents a sub-pixel that emits one of red, green,blue, and white light as described above.

The peripheral area PA is an area that does not provide an image andincludes a scan driver, a data driver and power lines. In such anembodiment, the scan driver and the data driver provide an electricsignal to be applied to pixels PX in the display area DA, and the powerlines provides power such as a driving voltage and a common voltage.

FIGS. 2A to 2C are equivalent circuit diagrams of one of the pixels of adisplay device according to embodiments.

Referring to FIG. 2A, in an embodiment, each pixel PX includes a pixelcircuit PC and an organic light-emitting diode OLED, the pixel circuitPC connected to a scan line SL and a data line DL, and the organiclight-emitting diode OLED connected to the pixel circuit PC.

The pixel circuit PC includes a driving thin film transistor T1, aswitching thin film transistor T2, and a storage capacitor Cst. Theswitching thin film transistor T2 is connected to the scan line SL andthe data line DL, and transfers a data signal Dm input to the data lineDL to the driving thin film transistor T1 in response to a scan signalSn input to the scan line SL.

The storage capacitor Cst is connected to the switching thin filmtransistor T2 and the driving voltage line PL and stores a voltagecorresponding to a difference between a voltage transferred from theswitching thin film transistor T2 and a first power voltage ELVDD (or adriving power voltage) supplied to the driving voltage line PL.

The first thin film transistor T1 may be connected to the drivingvoltage line PL and the storage capacitor Cst and may control a drivingcurrent flowing through the organic light-emitting diode OLED from thedriving voltage line PL in response to the voltage stored in the storagecapacitor Cst. The organic light-emitting diode OLED may emit lighthaving a predetermined brightness corresponding to the driving current.

FIG. 2A shows an embodiment where the pixel circuit PC includes two thinfilm transistors and a single storage capacitor, but embodiments are notlimited thereto.

Referring to FIG. 2B, in an alternative embodiment, the pixel circuit PCmay include the driving thin film transistor T1, the switching thin filmtransistor T2, a compensation thin film transistor T3, a firstinitialization thin film transistor T4, an operation control thin filmtransistor T5, an emission control thin film transistor T6, and a secondthin film transistor T7.

FIG. 2B shows an embodiment where each pixel PX includes signal linesSLn, SLn−1, EL, and DL, an initialization voltage line VL, and thedriving voltage line PL, but embodiments are not limited thereto. Inanother alternative embodiment, at least one of the signal lines SLn,SLn−1, EL, and DL, and the initialization voltage line VL may be sharedby a neighboring pixel.

A drain electrode of the driving thin film transistor T1 is electricallyconnected to an organic light-emitting diode OLED through the emissioncontrol thin film transistor T6. The driving thin film transistor T1receives a data signal Dm based on a switching operation of theswitching thin film transistor T2 and supplies a driving current to theorganic light-emitting diode OLED.

A gate electrode of the switching thin film transistor T2 is connectedto the scan line SLn, and a source electrode of the switching thin filmtransistor T2 is connected to the data line DL. A drain electrode of theswitching thin film transistor T2 is connected to the source electrodeof the driving thin film transistor T1 and also connected to the drivingvoltage line PL through the operation control thin film transistor T5.

The switching thin film transistor T2 is turned on in response to a scansignal Sn transferred through the scan line SLn and performs a switchingoperation of transferring a data signal Dm transferred through the dataline DL to the source electrode of the driving thin film transistor T1.

A gate electrode of the compensation thin film transistor T3 may beconnected to the scan line SLn. A source electrode of the compensationthin film transistor T3 is connected to the drain electrode of thedriving thin film transistor T1 and also connected to the pixelelectrode of the organic light-emitting diode OLED through the emissioncontrol thin film transistor T6. A drain electrode of the compensationthin film transistor T3 is connected to one of the electrodes of thestorage capacitor Cst, a source electrode of the first initializationthin film transistor T4, and the gate electrode of the driving thin filmtransistor T1. The compensation thin film transistor T3 is turned on inresponse to a scan signal Sn transferred through the scan line SLn anddiode-connects the driving thin film transistor T1 by connecting thegate electrode to the drain electrode of the driving thin filmtransistor T1.

A gate electrode of the first initialization thin film transistor T4 isconnected to a previous scan line SLn−1. A drain electrode of the firstinitialization thin film transistor T4 may be connected to theinitialization voltage line VL. A source electrode of the firstinitialization thin film transistor T4 may be connected to one of theelectrodes of the storage capacitor Cst, the drain electrode of thecompensation thin film transistor T3, and the gate electrode of thedriving thin film transistor T1. The first initialization thin filmtransistor T4 is turned on in response to a previous scan signal Sn−1transferred through the previous scan line SLn−1 and performs aninitialization operation of transferring an initialization voltage VINTto the gate electrode of the driving thin film transistor T1, therebyinitializing a voltage of the gate electrode of the driving thin filmtransistor T1.

A gate electrode of the operation control thin film transistor T5 may beconnected to the emission control line EL. A source electrode of theoperation control thin film transistor T5 may be connected to thedriving voltage line PL. A drain electrode of the operation control thinfilm transistor T5 is connected to the source electrode of the drivingthin film transistor T1 and the drain electrode of the switching thinfilm transistor T2.

A gate electrode of the emission control thin film transistor T6 may beconnected to the emission control line EL. A source electrode of theemission control thin film transistor T6 may be connected to the drainelectrode of the driving thin film transistor T1 and the sourceelectrode of the compensation thin film transistor T3. A drain electrodeof the emission control thin film transistor T6 may be electricallyconnected to the pixel electrode of the organic light-emitting diodeOLED. The operation control thin film transistor T5 and the emissioncontrol thin film transistor T6 are simultaneously turned on in responseto an emission control signal En transferred through the emissioncontrol line EL, and the first power voltage ELVDD is transferred to theorganic light-emitting diode OLED and the driving current flows throughthe organic light-emitting diode OLED.

A gate electrode of the second initialization thin film transistor T7may be connected to the previous scan line SLn−1. A source electrode ofthe second initialization thin film transistor T7 may be connected tothe pixel electrode of the organic light-emitting diode OLED. A drainelectrode of the second initialization thin film transistor T7 may beconnected to the initialization voltage line VL. The secondinitialization thin film transistor T7 is turned on in response to aprevious scan signal Sn−1 transferred through the previous scan lineSLn−1 and may initialize the pixel electrode of the organiclight-emitting diode OLED.

FIG. 2B shows an embodiment where the first initialization thin filmtransistor T4 and the second initialization thin film transistor T7 areconnected to the previous scan line SLn−1, but embodiments are notlimited thereto. In another alternative embodiment, the firstinitialization thin film transistor T4 may be connected to the previousscan line SLn−1 and driven in response to a previous scan signal Sn−1,and the second initialization thin film transistor T7 may be connectedto a separate signal line (for example, the next scan line) and drivenin response to a signal transferred through the relevant scan line.

The other electrode of the storage capacitor Cst may be connected to thedriving voltage line PL. One of the electrodes of the storage capacitorCst may be connected to the gate electrode of the driving thin filmtransistor T1, the drain electrode of the compensation thin filmtransistor T3, and the source electrode of the first initialization thinfilm transistor T4.

An opposite electrode (e.g. a cathode) of the organic light-emittingdiode OLED receives a second power voltage ELVSS (or a common powervoltage). The organic light-emitting diode OLED receives the drivingcurrent from the driving thin film transistor T1, thereby emittinglight.

The pixel circuit PC is not limited to the number of thin filmtransistors, the number of storage capacitors, and the circuit designdescribed with reference to FIGS. 2A and 2B. The number of the thin filmtransistors, the number of the storage capacitors, and the circuitdesign may be variously modified. Though not shown in the pixel circuitPC, a bias electrode may be further provided, and the bias electrode maybe arranged below the thin film transistors and connected to a thin filmtransistor.

Referring to FIG. 2C, in another alternative embodiment, each pixel PXmay include an organic light-emitting diode OLED, and the pixel circuitPC including a plurality of thin film transistors that drive the organiclight-emitting diode OLED. The pixel circuit PC may include the drivingthin film transistor T1, the switching thin film transistor T2, thesensing thin film transistor T3, and the storage capacitor Cst.

A scan line SL is connected to a gate electrode G2 of the switching thinfilm transistor T2, the data line DL is connected to a source electrodeS2 of the switching thin film transistor T2, and a first electrode CE1of the storage capacitor Cst may be connected to a drain electrode D2 ofthe switching thin film transistor T2.

Therefore, the switching thin film transistor T2 supplies a data voltageof the data line DL to a first node N in response to a scan signal Snfrom the scan line SL of each pixel PX.

A gate electrode G1 of the driving thin film transistor T1 may beconnected to the first node N, a source electrode S1 of the driving thinfilm transistor T1 may be connected to a first power line PL1 fortransferring the driving power voltage ELVDD, and a drain electrode D1may be connected to an anode electrode of the organic light-emittingdiode OLED.

In such an embodiment, the driving thin film transistor T1 may adjustthe amount of current flowing through the organic light-emitting diodeOLED based on a gate-source voltage Vgs of the driving thin filmtransistor T1 itself, that is, a voltage applied between the drivingpower voltage ELVDD and the first node N.

A sensing control line SSL is connected to a gate electrode G3 of thesensing thin film transistor T3, a source electrode S3 of the sensingthin film transistor T3 is connected to a second node S, and a drainelectrode D3 of the sensing thin film transistor T3 is connected to areference voltage line RL. In an embodiment, the sensing thin filmtransistor T3 may be controlled by the scan line SL instead of thesensing control line SSL.

The sensing thin film transistor T3 may sense an electric potential ofan anode electrode of the organic light-emitting diode OLED. The sensingthin film transistor T3 supplies a pre-charging voltage from thereference voltage line RL to the second node S, or supplies a voltage ofthe anode electrode AD of the organic light-emitting diode OLED to thereference voltage line RL during a sensing period in response to asensing signal SSn from the sensing control line SSL.

The first electrode CE1 of the storage capacitor Cst is connected to thefirst node N, and the second electrode CE2 of the storage capacitor Cstis connected to the second node S. The storage capacitor Cst is chargedwith a voltage corresponding to a voltage difference between voltagesrespectively supplied to the first node N and the second node S, and thestorage capacitor Cst supplies the charged voltage as a driving voltageof the driving thin film transistor T1. In one embodiment, for example,the storage capacitor Cst may be charged with a difference voltagebetween a data voltage Dm and a pre-charging voltage Vpre respectivelysupplied to the first node N and the second node S.

A bias electrode BSM may correspond to the driving thin film transistorT1 and connected to the source electrode S3 of the sensing thin filmtransistor T3. Since the bias electrode BSM receives a voltage incooperation with an electric potential of the source electrode S3 of thesensing thin film transistor T3, the driving thin film transistor T1 maybe stabilized. In an embodiment, the bias electrode BSM is not connectedto the source electrode S3 of the sensing thin film transistor T3 andmay be connected to a separate bias wiring.

An opposite electrode (e.g. a cathode) of the organic light-emittingdiode OLED receives a common power voltage ELVSS. The organiclight-emitting diode OLED receives a driving current from the drivingthin film transistor T1, thereby emitting light.

FIG. 2C shows an embodiment where the signal lines SL, SSL, and DL, thereference voltage line RL, the first power line PL1 and the second powerline PL2 are provided for each pixel PX, but embodiments are not limitedthereto. In one alternative embodiment, for example, at least one of thesignal lines SL, SSL, and DL, the reference voltage line RL, the firstpower line PL1, and the second power line PL2 may be shared byneighboring pixels.

FIG. 3 is a cross-sectional view of a display device according to anembodiment.

Referring to FIG. 3, an embodiment of the display may include a firstthin film transistor T1, a second thin film transistor T2, an organiclight-emitting diode OLED, which is a display element, a wiring WLincluding a first wiring layer DL1 and a second wiring layer DL2, afirst pattern insulating layer 114 a, a planarization layer 117 and aconnection electrode CM, which are over a substrate 110.

The first thin film transistor T1 may be connected to the organiclight-emitting diode OLED and may serve as a driving thin filmtransistor. The second thin film transistor T2 may be connected to thewiring WL such as a data line and may serve as a switching thin filmtransistor.

The first thin film transistor T1 may include a first semiconductorlayer A1, a first gate electrode G1, a first drain electrode D1, and afirst source electrode S1. The second thin film transistor T2 mayinclude a second semiconductor layer A2, a second gate electrode G2, asecond drain electrode, and a second source electrode S2.

In an embodiment, as shown in FIG. 3, the wiring WL includes the firstwiring layer DL1 and the second wiring layer DL2, such that an electricresistance of the wiring WL may be reduced. Therefore, in such anembodiment, the display device may be driven at high speed.

The first pattern insulating layer 114 a may be arranged between thefirst wiring layer DL1 and the second wiring layer DL2 of the wiring WL.The first pattern insulating layer 114 a may be simultaneously formedduring a process of forming the second wiring layer DL2. Therefore, anarea of a bottom surface of the second wiring layer DL2 may besubstantially the same as an area of a top surface of the first patterninsulating layer 114 a. In such an embodiment, a lateral surface of thesecond wiring layer DL2 may be connected to a lateral surface of thefirst pattern insulating layer 114 a, that is, the lateral surface ofthe second wiring layer DL2 and the lateral surface of the first patterninsulating layer 114 a may collectively define a same lateral surface.

In an embodiment, where the first pattern insulating layer 114 a isarranged between the first wiring layer DL1 and the second wiring layerDL2, a connection electrode CM may be arranged to connect the firstwiring layer DL1 to the second wiring layer DL2. The connectionelectrode CM may include a same material as a material of a pixelelectrode 210 of the organic light-emitting diode OLED described belowand may be arranged directly on a same layer on which the pixelelectrode 210 is arranged or the connection electrode CM may be disposedin a same layer as the pixel electrode 210.

The connection electrode CM may be arranged on a layer different from alayer on which the first wiring layer DL1 and the second wiring layerDL2 are arranged, or the connection electrode CM may be disposed in adifferent layer from the first wiring layer DL1 and the second wiringlayer DL2. Accordingly, the connection electrode CM may be connected tothe first wiring layer DL1 through a first contact hole CNT1 defined inthe planarization layer 117 and connected to the second wiring layer DL2through a second contact hole CNT2 defined in the planarization layer117. The first wiring layer DL1 and the second wiring layer DL2 arerespectively connected to the connection electrode CM through the firstcontact hole CNT1 and the second contact hole CNT2. In such anembodiment, an area of the first wiring layer DL1 may be different froman area of the second wiring layer DL2 such that the contact holes, thatis, the first contact hole CNT1 and the second contact hole CNT2 may besecured.

A stacked structure of an embodiment of a display device willhereinafter be described in detail with reference to FIG. 3.

In an embodiment, the substrate 110 may include a glass material, aceramic material, a metal material, or a flexible or bendable material.In an embodiment where the substrate 110 includes a flexible or bendablematerial, the substrate 110 may include a polymer resin such aspolyethersulfone (“PES”), polyarylate, polyetherimide (“PEI”),polyethylene naphthalate (“PEN”), polyethylene terephthalate (“PET”),polyphenylene sulfide (“PPS”), polyimide (“PI”), polycarbonate (“PC”) orcellulose acetate propionate (“CAP”), for example. The substrate 110 mayhave a single or multi-layered structure, each layer including at leastone selected from the above materials. In an embodiment, where thesubstrate 110 has a multi-layered structure, the substrate 110 mayfurther include an inorganic layer. In an embodiment, the substrate 110may have a structure of an organic material/an inorganic material/anorganic material.

The buffer layer 111 is disposed over an entire top surface of thesubstrate 110 and may have a structure in which a first buffer layer 111a and a second buffer layer 111 b are stacked one on another. The bufferlayer 111 may increase flatness of a top surface of the substrate 110and include an inorganic material such as silicon oxide, siliconnitride, and/or silicon oxynitride. In an embodiment, the buffer layer111 may serve as a barrier layer. The buffer layer 111 may effectivelyprevent or minimize penetration of impurities from the substrate 110,etc. into the first and second semiconductor layers A1 and A2. The firstbuffer layer 111 a may include a material that is the same as ordifferent from a material of the second buffer layer 111 b. In anembodiment, each of the first buffer layer 111 a and the second bufferlayer 111 b may have a single or multi-layered structure.

The bias electrode BSM may be arranged between the first buffer layer111 a and the second buffer layer 111 b. The bias electrode BSM may bearranged to overlap at least a portion of the first thin film transistorT1 and may be connected to the first drain electrode D1 of the firstthin film transistor T1. In such an embodiment, the bias electrode BSMreceives a voltage of an electric potential of the first drain electrodeD1 of the first thin film transistor T1, such that the driving thin filmtransistor T1 may be stabilized. In an alternative embodiment, the biaselectrode BSM may not be connected to the first drain electrode D1 ofthe first thin film transistor T1 and may be connected to a separatebias wiring.

The first and second semiconductor layers A1 and A2 may be arranged onthe buffer layer 111. The first and second semiconductor layers A1 andA2 may include amorphous silicon or polycrystalline silicon. In analternative embodiment, the first and second semiconductor layers A1 andA2 may include an oxide of at least one selected from In, Ga, Sn, Zr, V,Hf, Cd, Ge, Cr, Ti and Zn. The first and second semiconductor layers A1and A2 may include a channel region, a source region and a drain region,and the source region and the drain region may be doped with impurities.

The first and second gate electrodes G1 and G2 are arranged over thefirst and second semiconductor layers A1 and A2 with a gate insulatinglayer 112 therebetween. The first and second gate electrodes G1 and G2may include at least one selected from Mo, Al, Cu and Ti, and may have asingle or multi-layered structure. In one embodiment, for example, thefirst and second gate electrodes G1 and G2 may include a single Molayer.

The gate insulating layer 112 may include SiO₂, SiN_(x), SiON, Al₂O₃,TiO₂, Ta₂O₅, HfO₂, or ZnO₂.

In an embodiment, as shown in FIG. 3, the gate insulating layer 112 maybe patterned in a same shape as those of the first gate electrode G1 andthe second gate electrode G2. However, embodiments are not limitedthereto. Alternatively, the gate insulating layer 112 may be disposedover an entire top surface of the substrate 110.

In an embodiment where the gate insulating layer 112 is patterned asshown in FIG. 3, the first electrode CE1 of the storage capacitor Cstmay be arranged on a top surface of the buffer layer 111. The firstelectrode CE1 may include a same material as those of the first andsecond gate electrodes G1 and G2 and may be formed during a same processas a process of forming the first and second gate electrodes G1 and G2.The first electrode CE1 may include at least one selected from Mo, Al,Cu and Ti, and may have a single or multi-layered structure.

A first interlayer insulating layer 113 may cover the first and secondgate electrodes G1 and G2, and the first electrode CE1. The firstinterlayer insulating layer 113 may include SiO₂, SiN_(x), SiON, Al₂O₃,TiO₂, Ta₂O₅, HfO₂, or ZnO₂.

The first and second source electrodes S1 and S2 respectively of thefirst and second thin film transistors T1 and T2, the first drainelectrode D1, the first wiring layer DL1, and the second electrode CE2of the storage capacitor Cst may be arranged on the first interlayerinsulating layer 113.

In an embodiment, the second electrode CE2 of the storage capacitor Cstoverlaps the first electrode CE1 and the first interlayer insulatinglayer 113 is disposed therebetween. In such an embodiment, the firstinterlayer insulating layer 113 may serve as a dielectric layer of thestorage capacitor Cst.

The first and second source electrodes S1 and S2, the first drainelectrode D1, the first wiring layer DL1, and the second electrode CE2of the storage capacitor Cst may include a conductive material includingat least one selected from Mo, Al, Cu and Ti, and may have a single ormulti-layered structure, each layer including at least one selected fromthe above materials. In an embodiment, the first and second sourceelectrodes S1 and S2, the first drain electrode D1, the first wiringlayer DL1, and the second electrode CE2 of the storage capacitor Cst mayhave a multi-layered structure of Ti/Al/Ti.

The first and second source electrodes S1 and S2 and the first drainelectrode D1 may be connected to the first and second semiconductorlayers A1 and A2 through contact holes defined through the firstinterlayer insulating layer 113. A portion of the first wiring layer DL1of the wiring WL may extend to serve as the second source electrode S2.In such an embodiment, the first wiring layer DL1 and the second sourceelectrode S2 may define, or be integrally formed as, a single unitarybody.

Pattern insulating layers 114 a, 114 b, and 114 c may be arranged on thefirst and second source electrodes S1 and S2, the first drain electrodeD1, and the first wiring layer DL1. The pattern insulating layers 114 a,114 b, and 114 c may include SiO₂, SiN_(x), SiON, Al₂O₃, TiO₂, Ta₂O₅,HfO₂, or ZnO₂.

The pattern insulating layers 114 a, 114 b, and 114 c may include afirst pattern insulating layer 114 a, a second pattern insulating layer114 b, and a third pattern insulating layer 114 c. The first patterninsulating layer 114 a may be arranged to correspond to the first wiringlayer DL1 and may expose a portion of the first wiring layer DL1. Thesecond pattern insulating layer 114 b may be arranged to correspond tothe first drain electrode D1 and may expose a portion of the first drainelectrode D1. The third pattern insulating layer 114 c may be arrangedto correspond to the first source electrode S1 and may expose a portionof the first source electrode S1.

The second wiring layer DL2, a first additional drain electrode D1′, anda second additional source electrode S1′ may be arranged on the patterninsulating layers 114 a, 114 b, and 114 c. The second wiring layer DL2,the first additional drain electrode D1′, and the second additionalsource electrode S1′ may include a conductive material including atleast one selected from Mo, Al, Cu and Ti, and may have a single ormulti-layered structure, each layer including at least one selected fromthe above materials. In one embodiment, for example, the second wiringlayer DL2, the first additional drain electrode D1′, and the secondadditional source electrode S1′ may have a multi-layered structure ofTi/Al/Ti.

The pattern insulating layers 114 a, 114 b, and 114 c may be formed byetching during a same process as a process of forming the second wiringlayer DL2, the first additional drain electrode D1′, and the secondadditional source electrode S1′ arranged thereon.

The planarization layer 117 covers the second wiring layer DL2, thefirst additional drain electrode D1′, and the second additional sourceelectrode S1′. The planarization layer 117 may include an organicmaterial such as acryl, benzocyclobutene (“BCB”), PI, orhexamethyldisiloxane (“HMDSO”). Alternatively, the planarization layer117 may include an inorganic material. The planarization layer 117 maygenerally planarize a protective layer covering the first and secondthin film transistors T1 and T2 and the wiring WL. The planarizationlayer 117 may have a single or multi-layered structure. in anembodiment, where the pattern insulating layers 114 a, 114 b, and 114 care patterned, the planarization layer 117 may contact lateral surfacesof the pattern insulating layers 114 a, 114 b, and 114 c.

The connection electrode CM, the pixel electrode 210, and a sourceconnection electrode CM′ may be arranged on the planarization layer 117.The connection electrode CM may be connected to the first wiring layerDL1 and the second wiring layer DL2 respectively through the firstcontact hole CNT1 and the second contact hole CNT2 defined in theplanarization layer 117. The pixel electrode 210 may be one electrode ofthe organic light-emitting diode OLED and serve as a drain connectionelectrode connecting the first drain electrode D1 to the firstadditional drain electrode D1′. The pixel electrode 210 may be connectedto the first drain electrode D1 and the first additional drain electrodeD1′ through contact holes defined in the planarization layer 117. Insuch an embodiment, the source connection electrode CM′ may connect thefirst source electrode S1 to the first additional source electrode S1′through a contact hole defined in the planarization layer 117.

The connection electrode CM, the pixel electrode 210, and the sourceconnection electrode CM′ each may include a (semi) transmissiveelectrode or a reflective electrode. In an embodiment, the connectionelectrode CM, the pixel electrode 210, and the source connectionelectrode CM′ may include a reflective layer and a transparent orsemi-transparent electrode layer on the reflective layer, and thereflective layer may include at least one selected from Ag, Mg, Al, Pt,Pd, Au, Ni, Nd, Ir, Cr and a compound thereof. The transparent orsemi-transparent electrode layer may include at least one selected fromindium tin oxide (“ITO”), indium zinc oxide (“IZO”), zinc oxide (ZnO),or indium oxide (In₂O₃), indium gallium oxide (“IGO”), and aluminum zincoxide (“AZO”). In an embodiment, the connection electrode CM, the pixelelectrode 210, and the source connection electrode CM′ may have astacked structure of ITO/Ag/ITO.

A pixel-defining layer 119 may be arranged on the connection electrodeCM, the pixel electrode 210, and the source connection electrode CM′.The pixel-defining layer 119 defines a pixel by an opening definedtherethrough to correspond to each sub-pixel, that is, an opening thatexposes at least a central portion of the pixel electrode 210. In anembodiment, the pixel-defining layer 119 may prevent an arc, etc. fromoccurring at edges of the pixel electrode 210 by increasing a distancebetween the edges of the pixel electrode 210 and an opposite electrode230 over the edges of the pixel electrode 210. The pixel-defining layer119 may include an organic material such as PI or HMDSO.

An intermediate layer 220 of the organic light-emitting diode OLED mayinclude a low molecular weight material or a polymer material. In anembodiment where the intermediate layer 220 includes a low molecularweight material, the intermediate layer 220 may have a structure inwhich a hole injection layer (“HIL”), a hole transport layer (“HTL”), anemission layer (“EML”), an electron transport layer (“ETL”), an electroninjection layer (“EIL”), etc. are stacked in a single or a compositeconfiguration. The intermediate layer 220 may include at least oneselected from various organic materials such as copper phthalocyanine(“CuPc”), N, N′-Di (naphthalene-1-yl)-N,N′-diphenyl-benzidine (“NPB”),and tris-8-hydroxyquinoline aluminum (“Alq3”). These layers may beformed by a vacuum deposition.

In an embodiment where the intermediate layer 220 includes a polymermaterial, the intermediate layer 220 may have a structure generallyincluding an HTL and an EML. In such an embodiment, the HTL may includepoly(3,4-ethylenedioxythiophene) polystyrene sulfonate (“PEDOT”), andthe EML may include a polymer material such as a polyphenylene vinylene(“PPV”)-based material and a polyfluorene-based material. Theintermediate layer 220 may be formed by a screen printing, an inkjetprinting or a laser induced thermal imaging (“LITI”), for example.

In an embodiment, the structure of the intermediate layer 220 is notlimited those described above, but may be variously modified. In anembodiment, the intermediate layer 220 may include a layer which is asingle unit over a plurality of pixel electrodes 210, or include apatterned layer corresponding to each of the plurality of pixelelectrodes 210.

The opposite electrode 230 may be integrally formed as a single unitaryindivisible unit over a plurality of organic light-emitting diodes andmay correspond to a plurality of pixel electrodes 210. The oppositeelectrode 230 may include a conductive material having a low workfunction. In one embodiment, for example, the opposite electrode 230 mayinclude a (semi) transparent layer including Ag, Mg, Al, Pt, Pd, Au, Ni,Nd, Ir, Cr, Li, Ca, or an alloy thereof. Alternatively, the oppositeelectrode 230 may further include a layer including ITO, IZO, ZnO, orIn₂O₃ on the (semi) transparent layer including at least one selectedfrom the above material.

FIGS. 4 to 11 are sequential cross-sectional views of a method ofmanufacturing a display device, according to an embodiment.

In an embodiment, referring to FIG. 4, the first thin film transistorT1, the second thin film transistor T2 and the storage capacitor Cst areprovided or formed over the substrate 110. The first electrode CE1 ofthe storage capacitor Cst may be simultaneously formed with the firstand second gate electrodes G1 and G2 during the same process as aprocess of forming the first and second gate electrodes G1 and G2 of thefirst and second thin film transistors T1 and T2. The second electrodeCE2 of the storage capacitor Cst may be simultaneously formed with thefirst wiring layer DL1, the first and second source electrodes S1 andS2, and the first drain electrode D1 during the same process as aprocess of forming the first wiring layer DL1, the first and secondsource electrodes S1 and S2, and the first drain electrode D1. In suchan embodiment, as described above, since a separate process is notperformed to form the storage capacitor Cst in the display device,manufacturing costs and time may be reduced.

In an embodiment, a second interlayer insulating layer 114 is providedor formed on an entire top surface of the substrate 110 to cover thefirst and second source electrodes S1 and S2 of the first and secondthin film transistors T1 and T2, the first drain electrode D1, the firstwiring layer DL1, and the storage capacitor Cst.

The second interlayer insulating layer 114 may include SiO₂, SiN_(x),SiON, Al₂O₃, TiO₂, Ta₂O₅, HfO₂, or ZnO₂. The second interlayerinsulating layer 114 may be formed by using at least one of variousdeposition methods such as a chemical vapor deposition (“CVD”) and asputtering.

In such an embodiment, a conductive layer CL is provided or formed overan entire top surface of the second interlayer insulating layer 114. Theconductive layer CL may include a conductive material including Mo, Al,Cu or Ti and have a single or multi-layered structure, including atleast one selected from the above materials.

The conductive layer CL may be formed by a deposition method such as aplasma enhanced CVD (“PECVD”), a low pressure CVD (“LPCVD”), a physicalvapor deposition (“PVD”), a sputtering or an atomic layer deposition(“ALD”), but not being limited thereto.

In such an embodiment, referring to FIG. 6, a photoresist (“PR”) patternis formed on the conductive layer CL through a photolithography process.The photolithography process includes coating a photosensitive materialon the conductive layer CL, irradiating light on the photosensitivematerial by using a mask, and then forming a PR pattern throughhardening and developing processes. The PR pattern may be formed tocorrespond to areas in which the second wiring layer DL2, the firstadditional drain electrode D1′ and the first additional source electrodeS1′, which will be described below, are formed.

In an embodiment, referring to FIG. 7, a process of etching theconductive layer CL and the second interlayer insulating layer 114 byusing the PR pattern as an etch mask is performed. In such anembodiment, the second wiring layer DL2, the first additional drainelectrode D1′ and the first additional source electrode S1′ may beformed by etching the conductive layer CL. In an embodiment, a firstpattern insulating layer 114 a, a second pattern insulating layer 114 band a third pattern insulating layer 114 c may be formed using the PRpattern, the second wiring layer DL2, the first additional drainelectrode D1′ and the first additional source electrode S1′ as etchmasks for the second interlayer insulating layer 114.

The conductive layer CL and the second interlayer insulating layer 114may be sequentially etched, and etching conditions thereof may bedifferent from each other. The etching may be performed by a dryetching, a wet etching or a combination thereof. In such an embodiment,as described above, the process of etching the second interlayerinsulating layer 114 may be performed without a separate mask process,such that manufacturing costs and time may be reduced during a process.

In an embodiment, referring to FIGS. 8 and 9, the PR pattern used as anetch mask is removed, and the planarization layer 117 is provided orformed on an entire top surface of the first interlayer insulating layer113 to cover the second wiring layer DL2, the first additional drainelectrode D1′ and the first additional source electrode S1′.

In an embodiment, an organic material such as acryl, BCB, PI or HMDSO iscoated on the entire top surface of the first interlayer insulatinglayer 113 to cover the second wiring layer DL2, the first additionaldrain electrode D1′ and the first additional source electrode S1′, andcontact holes such as the first contact hole CNT1 and the second contacthole CNT2 may be formed through a mask process to form the planarizationlayer 117. In such an embodiment, the holes expose the second wiringlayer DL2, the first additional drain electrode D1′, the firstadditional source electrode S1′, the first wiring layer DL1, the firstdrain electrode D1 and the first source electrode S1.

In an embodiment, referring to FIG. 10, the connection electrode CM, thepixel electrode 210 and the source connection electrode CM′ are providedor formed on the planarization layer 117. The connection electrode CM,the pixel electrode 210 and the source connection electrode CM′ may beformed by depositing a conductive layer on an entire top surface of theplanarization layer 117 and performing a mask process and an etchingprocess.

In such an embodiment, holes exposing the second wiring layer DL2, thefirst additional drain electrode D1′, the first additional sourceelectrode S1′, the first wiring layer DL1, the first drain electrode D1and the first source electrode S1 are formed in the planarization layer117, such that the connection electrode CM may connect the first wiringlayer DL1 to the second wiring layer DL2 through the holes. In such anembodiment, the pixel electrode 210 may connect the first drainelectrode D1 to the first additional drain electrode D1′, and the sourceconnection electrode CM′ may connect the first source electrode S1 tothe first additional source electrode S1′.

In an embodiment, referring to FIG. 11, the pixel-defining layer 119 isprovided or formed on an entire top surface of the planarization layer117 to cover edges of the pixel electrode 210, and an opening thatexposes a central portion of the pixel electrode 210 is formed throughthe pixel-defining layer 119. The intermediate layer 220 is provided orformed inside the opening. The intermediate layer 220 may include a lowmolecular weight material or a polymer material. The intermediate layer220 may be formed by a vacuum deposition method, a screen printing, aninkjet printing or an LITI.

In an embodiment, as shown in FIG. 11, the opposite electrode 230 isprovided or formed to correspond to a plurality of organiclight-emitting diodes OLED. The opposite electrode 230 may be formed byusing an open mask to cover the display area DA (see FIG. 1) of thesubstrate 110. The opposite electrode 230 may be formed by at least oneof deposition methods such as PECVD, LPCVD, PVD, a sputtering and anALD.

FIG. 12 is a cross-sectional view of a display device according to analternative embodiment. In FIG. 12, the same or like elements have beenlabeled with the same reference characters as used above to describeembodiments in FIG. 3, and any repetitive detailed description thereofwill hereinafter be omitted or simplified.

Referring to FIG. 12, an embodiment of the display device includes thefirst and second thin film transistors T1 and T2, an organiclight-emitting diode OLED, which is a display element connected to thefirst thin film transistor T1, the wiring WL connected to the secondthin film transistor T2 and including the first wiring layer DL1 and thesecond wiring layer DL2, the first pattern insulating layer 114 aarranged between the first wiring layer DL1 and the second wiring layerDL2, the planarization layer 117 covering the wiring WL, and theconnection electrode CM arranged on the planarization layer 117 andconnected to the first wiring layer DL1 and the second wiring layer DL2respectively through the first contact hole CNT1 and the second contacthole CNT2.

In such an embodiment, the wiring WL includes the first wiring layer DL1and the second wiring layer DL2, such that an electric resistance of thewiring WL is reduced and thus a high-speed driving may be effectivelyrealized.

In an embodiment, as shown in FIG. 12, a thin-film encapsulation layer300 may be disposed on the organic light-emitting diode OLED. In such anembodiment, the thin-film encapsulation layer 300 may protect theorganic light-emitting diodes OLED, which may be easily damaged byexternal moisture or oxygen, by covering the organic light-emittingdiodes OLED. The thin-film encapsulation layer 300 may cover the displayarea DA (see FIG. 1) and extend to the peripheral area PA (see FIG. 1)outside the display area DA. The thin-film encapsulation layer 300 mayinclude a first inorganic encapsulation layer 310, an organicencapsulation layer 320, and a second inorganic encapsulation layer 330.

The first inorganic encapsulation layer 310 may cover the oppositeelectrode 230 and include a ceramic, a metal oxide, a metal nitride, ametal carbide, a metal oxynitride, indium oxide (In₂O₃), zinc oxide(SnO₂), ITO, silicon oxide, silicon nitride, and/or silicon oxynitride.Alternatively, other layers such as a capping layer may be arrangedbetween the first inorganic encapsulation layer 310 and the oppositeelectrode 230. Since the first inorganic encapsulation layer 310 isdisposed or formed along a structure thereunder, a top surface of thefirst inorganic encapsulation layer 310 may not be flat.

The organic encapsulation layer 320 covers the first inorganicencapsulation layer 310. In an embodiment, a top surface of the organicencapsulation layer 320 may be approximately flat. In such anembodiment, a top surface of the organic encapsulation layer 320 thatcorresponds to the display area DA may be approximately flat. Theorganic encapsulation layer 320 may include at least one of acrylic, metacrylic, polyester, polyethylene, polypropylene, PET, PEN, PC, PI,polyethylene sulfonate, polyoxymethylene, polyarylate, and HMDSO.

The second inorganic encapsulation layer 330 may cover the organicencapsulation layer 320 and include a ceramic, a metal oxide, a metalnitride, a metal carbide, a metal oxynitride, indium oxide (In₂O₃), zincoxide (SnO₂), ITO, silicon oxide, silicon nitride, and/or siliconoxynitride.

Since the thin-film encapsulation layer 300 includes the first inorganicencapsulation layer 310, the organic encapsulation layer 320, and thesecond inorganic encapsulation layer 330 as described above, even when acrack occurs inside the thin-film encapsulation layer 300, the thin-filmencapsulation layer 300 may effectively prevent cracks from beingconnected to each other through such a multi-layered structure, thecracks occurring between the first inorganic encapsulation layer 310 andthe organic encapsulation layer 320 or between the organic encapsulationlayer 320 and the second inorganic encapsulation layer 330. In such anembodiment, forming of a path through which external moisture or oxygenmay penetrate into the display area DA may be effectively prevented orminimized.

In an embodiment, a spacer (not shown) for preventing mask chopping maybe further provided on the pixel-defining layer 119. In an embodiment,at least one of various functional layers including a polarization layerfor reducing external light reflection, a black matrix, a color filterand/or a touchscreen layer including a touch electrode may be providedon the thin-film encapsulation layer 300.

FIG. 13 is a cross-sectional view of a display device according toanother alternative embodiment. In FIG. 13, the same or like elementshave been labeled with the same reference characters as used above todescribe embodiments in FIG. 3, and any repetitive detailed descriptionthereof will hereinafter be omitted or simplified.

Referring to FIG. 13, an embodiment of the display device includes thefirst and second thin film transistors T1 and T2, an organiclight-emitting diode OLED, which is a display element connected to thefirst thin film transistor T1, the wiring WL connected to the secondthin film transistor T2 and including the first wiring layer DL1 and thesecond wiring layer DL2, the first pattern insulating layer 114 aarranged between the first wiring layer DL1 and the second wiring layerDL2, the planarization layer 117 covering the wiring WL, and theconnection electrode CM arranged on the planarization layer 117 andconnected to the first wiring layer DL1 and the second wiring layer DL2respectively through the first contact hole CNT1 and the second contacthole CNT2.

In such an embodiment, the wiring WL includes the first wiring layer DL1and the second wiring layer DL2, such that an electric resistance of thewiring WL is reduced and thus a high-speed driving is effectivelyrealized.

In an embodiment, as shown in FIG. 13, a sealing substrate 300′ facingthe substrate 110 may be further provided, where the sealing substrate300′ seals the organic light-emitting diode OLED. In such an embodiment,the organic light-emitting diode OLED may be arranged between thesubstrate 110 and the sealing substrate 300′. The sealing substrate 300′may include a glass or a polymer resin. The substrate 110 and thesealing substrate 300′ may be attached to each other by a sealingmaterial such as sealant or frit, and the sealing material is arrangedin the peripheral area PA (see FIG. 1) and at least partially surroundsthe display area DA. In such an embodiment, at least one of variousfunctional layers including a polarization layer for reducing externallight reflection, a black matrix, a color filter, and/or a touchscreenlayer including a touch electrode may be provided on the sealingsubstrate 300′.

In embodiments of the invention, as described above, since a data linefor providing a data signal, etc. are provided by using the first wiringlayer and the second wiring layer in a display device, low-resistancewirings may be implemented and thus high-speed driving is realized.

In embodiments of the invention, since a method of manufacturing adisplay device is performed with a minimized number of mask process,such that process time and costs may be reduced.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more embodiments have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope asdefined by the following claims.

What is claimed is:
 1. A display device comprising: a substrate; a first thin film transistor disposed over the substrate; a second thin film transistor disposed over the substrate; a display element connected to the first thin film transistor; a wiring connected to the second thin film transistor, wherein the wiring includes a first wiring layer and a second wiring layer; a pattern insulating layer disposed between the first wiring layer and the second wiring layer; a planarization layer covering the wiring; and a connection electrode disposed on the planarization layer and connected to the first wiring layer and the second wiring layer through a first contact hole and a second contact hole, respectively.
 2. The display device of claim 1, wherein a bottom surface of the second wiring layer has a same area as an area of a top surface of the pattern insulating layer.
 3. The display device of claim 1, wherein a lateral surface of the second wiring layer is connected to a lateral surface of the pattern insulating layer.
 4. The display device of claim 1, wherein the display element includes a pixel electrode, an emission layer, and an opposite electrode, and the connection electrode includes a same material as a material of the pixel electrode and is disposed in a same layer as the pixel electrode.
 5. The display device of claim 1, wherein an area of the first wiring layer is different from an area of the second wiring layer.
 6. The display device of claim 1, wherein the planarization layer contacts a lateral surface of the pattern insulating layer.
 7. The display device of claim 1, further comprising: a capacitor including a first electrode and a second electrode, wherein the first electrode including a same material as a material of a gate electrode of the first thin film transistor, and the second electrode overlaps the first electrode, includes a same material as a material of the first wiring layer, and is disposed in a same layer as the first wiring layer.
 8. The display device of claim 1, further comprising: a bias electrode disposed below the first thin film transistor.
 9. The display device of claim 8, wherein the bias electrode is connected to a source electrode or a drain electrode of the first thin film transistor.
 10. The display device of claim 1, wherein the wiring includes a data line which provides a data signal to the second thin film transistor.
 11. The display device of claim 1, further comprising: a thin-film encapsulation layer covering the display element, wherein the thin-film encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer and a second inorganic encapsulation layer, which are stacked one on another.
 12. The display device of claim 1, further comprising: a sealing substrate disposed opposite to the substrate.
 13. A method of manufacturing a display device, the method comprising: providing a thin film transistor and a first wiring layer connected to the thin film transistor over a substrate; sequentially providing an insulating layer and a conductive layer on an entire top surface of the substrate to cover the first wiring layer; providing a photoresist pattern on the conductive layer; forming a second wiring layer and a pattern insulating layer by etching the conductive layer and the insulating layer using the photoresist pattern as an etch mask; and providing a connection electrode connecting the first wiring layer to the second wiring layer.
 14. The method of claim 13, wherein a bottom surface of the second wiring layer has a same area as an area of a top surface of the pattern insulating layer.
 15. The method of claim 13, wherein a lateral surface of the second wiring layer is connected to a lateral surface of the pattern insulating layer.
 16. The method of claim 13, wherein a display element of the display device includes a pixel electrode, an emission layer, and an opposite electrode, and the connection electrode includes a same material as a material of the pixel electrode and is disposed in a same layer as the pixel electrode.
 17. The method of claim 13, wherein an area of the first wiring layer is different from an area of the second wiring layer.
 18. The method of claim 13, further comprising: providing a planarization layer covering the first wiring layer, the second wiring layer and the pattern insulating layer before the providing the connection electrode.
 19. The method of claim 13, further comprising: providing a capacitor including a first electrode and a second electrode, wherein the first electrode includes a same material as a material of a gate electrode of the thin film transistor, and the second electrode overlaps the first electrode, includes a same material as a material of the first wiring layer, and is disposed in a same layer as the first wiring layer.
 20. The method of claim 13, further comprising: providing a bias electrode arranged below the thin film transistor. 